undo a useless change

src/test/ui/async-await/async-error-span.rs

@@ -5,7 +5,8 @@
 use std::future::Future;
 
 fn get_future() -> impl Future<Output = ()> {
-    panic!() //~^ ERROR `()` is not a future
+//~^ ERROR `()` is not a future
+    panic!()
 }
 
 async fn foo() {

src/test/ui/async-await/async-error-span.stderr

@@ -8,13 +8,13 @@ LL | fn get_future() -> impl Future<Output = ()> {
    = note: () must be a future or must implement `IntoFuture` to be awaited
 
 error[E0698]: type inside `async fn` body must be known in this context
-  --> $DIR/async-error-span.rs:12:9
+  --> $DIR/async-error-span.rs:13:9
    |
 LL |     let a;
    |         ^ cannot infer type
    |
 note: the type is part of the `async fn` body because of this `await`
-  --> $DIR/async-error-span.rs:13:17
+  --> $DIR/async-error-span.rs:14:17
    |
 LL |     get_future().await;
    |                 ^^^^^^